Configuration notes for bgp4 autonomous systems – Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 User Manual
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Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Optional BGP4 configuration tasks
For more information about the neighbor command, refer to
By default, the clients of a route reflector are not required to be fully meshed; the routes from a
client are reflected to other clients. However, if the clients are fully meshed, route reflection is not
required between clients.
If you need to disable route reflection between clients, enter the following command. When the
feature is disabled, route reflection does not occur between clients but reflection does still occur
between clients and non-clients.
Brocade(config-bgp-router)#no client-to-client-reflection
Enter the following command to re-enable the feature.
Brocade(config-bgp-router)#client-to-client-reflection
Syntax: [no] client-to-client-reflection
Configuration notes for BGP4 autonomous systems
A confederation is a BGP4 Autonomous System (AS) that has been subdivided into multiple,
smaller autonomous systems. Subdividing an AS into smaller autonomous systems simplifies
administration and reduces BGP-related traffic, thus reducing the complexity of the Interior Border
Gateway Protocol (IBGP) mesh among the BGP routers in the AS.
The Brocade implementation of this feature is based on RFC 3065.
Normally, all BGP routers within an AS must be fully meshed, so that each BGP router has
interfaces to all the other BGP routers within the AS. This is feasible in smaller autonomous
systems but becomes unmanageable in autonomous systems containing many BGP routers.
When you configure BGP routers into a confederation, all the routers within a sub-AS (a subdivision
of the AS) use IBGP and must be fully meshed. However, routers use EBGP to communicate
between different sub-autonomous systems.
NOTE
Another method for reducing the complexity of an IBGP mesh is to use route reflection. However, if
you want to run different Interior Gateway Protocols (IGPs) within an AS, configure a confederation.
You can run a separate IGP within each sub-AS.
To configure a confederation, configure groups of BGP routers into sub-autonomous systems. A
sub-AS is simply an AS. The term “sub-AS” distinguishes autonomous systems within a
confederation from autonomous systems that are not in a confederation. For the viewpoint of
remote autonomous systems, the confederation ID is the AS ID. Remote autonomous systems do
not know that the AS represents multiple sub-autonomous systems with unique AS IDs.
NOTE
You can use any valid AS numbers for the sub-autonomous systems. If your AS is connected to the
Internet, Brocade recommends that you use numbers from within the private AS range (64512
through 65535). These are private autonomous systems numbers and BGP4 routers do not
propagate these AS numbers to the Internet.